Electrical switch having frictionally engaging contacts and fulcrum release means therefor



Dec. 6, 1966 D. N. SEWELL 3,290,470

ELECTRICAL SWITCH HAVING FRICTIONALLY ENGAGING CONTACTS AND FULCRUM RELEASE MEANS THEREFOR Filed May 19, 1965 2 Sheets-Sheet 1 Dec. 6, 1966 N. SEWELL 3,290,470

ELECTRICAL SWITCH HAV FRICTIONALLY ENGAGING CONTACTS AND FULCRUM RELEASE MEANS THEREFOR Filed May 19, 1965 2 Sheets-Sheet 2 United States PatentO 3,290,470 ELECTRICAL SWITCH HAVING FRICTIQNALLY ENGAGENG CONTACTS AND FULCRUM RE- LEASE MEAN THEREFOR Donald N. Sewell, Acton, Mass., assiguor to Dielectric Products Engineering Company Inc., Littleton, Mass., a corporation of Michigan Filed May 19, 1965, Ser. No. 457,035 7 Claims. (til. 200-153) This invention relates to electrical switch apparatus and more particularly to switch apparatus especially adapted for use in high frequency electrical transmission systems of the coaxial type.

The transmission of high frequency electrical signals involves electromagnetic fields associated with these signals that must be taken into account in the design both of transmission lines and of components utilized with such transmission lines. A commonly employed transmission line configuration for use for the transmission of high frequency electrical signals is the coaxial line which employs two conductors coaxially disposed with respect to one another. Such transmission lines are used for transmitting substantial quantities of high frequency power, and the sizes of standard impedance transmission lines may be as much as three inches in diameter or even larger. The design of switch components for use with lines of such size, particularly where switching in short intervals is desired, must take into account both the mechanical requirements for switch operation and the electromagnetic considerations such as minimizing insertion loss, distortion and interference. Also, the energy coupling from the transmission line section through which power is flowing to the disconnected transmission line section must be minimized in a double throw switch. Further, the design should minimize the possibility of impedance discontinuities in the transmission line due to the use of the switch.

It is an object of this invention to provide a novel and improved electrical switch structure particularly adapted for use with high frequency electrical coaxial lines.

A further object of the invention is to provide a novel and improved coaxial line electrical switch structure which has a switching time less than fifty milliseconds.

Another object of the invention is to provide a high speed microwave power switch device having a bearing structure that does not carry electrical current.

Still another object of the invention is to provide a novel and improved frictionally latched microwave switch structure having a cocking capability for high speed operation.

A SPDT electrical switch structure constructed in accordance with the invention includes two fixed contact structures, each being coupled to a corresponding line terminal. A current carrying switch arm includes two opposed contacts that are adapted to cooperate with the fixed contact structures. Each arm contact and the cooperating fixed contact structure frictionally engage one another so that they are secured in circuit completing position by substantial frictional force. The switch arm is mounted on an insulating pivot bearing and the circuit is completed to the common terminal by engagement of the switch arm with one or more contact structures that engage electrically conductive surfaces of the switch arm. An actuating lever is pivotally connected to the switch arm. This actuating lever includes the opposed pivot surfaces intermediate its ends, each of which engages a fixed fulcrum surface disposed adjacent each fixed contact structure. Biasing means extending between the actuating lever and the switch arm bridges the pivot connection between these two elements.

An operator coupled to the actuating lever moves the azaam Patented Dec. 6, 1966 lever from a first position in which one lever projection engages the cooperating one of the fixed fulcrum surfaces to a second position in which the other lever projection engages the other fixed fulcrum surface. No movement of the switch arm occurs during the movement of the actuating lever between the two fulcrum surfaces. As the actuating lever is moved further, it is rocked about the point of contact between its pivot surface and the fulcrum surface rather than about the pivot connection to the switch arm and this rocking action withdraws the switch arm contact from the engaged fixed contact structure. The switch structure is designed so that when the frictional engagement between the contacts is released (opening the electrical circuit), the biasing means has been moved to an over-center position so that it accelerates the switch arm rapidly into engagement with the other set of fixed contacts.

This resulting movement of the switch arm occurs as soon as it is frictionally released as a snap action having a high rate of acceleration so that switching time in a high power coaxial switch structure is less than fifty milliseconds. Further, the actuating lever may be moved after a switching operation into cocked position in engagement with the other fulcrum surface and held in that position so that in response to a switch request signal, levering action alone is required and thus the switching response is rapid. Other objects, features and advantages of the invention will be seen as the following description of a par: ticular embodiment thereof progresses, in conjunction with the drawings, in which:

FIG. 1 is a side elevational view (partially in section) of a switch structure constructed in accordance with the invention.

FIG. 2 is a sectional view of the switch structure shown in FIG. 1 taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view of the switch arm and supporting structure taken along the line 33 of FIG. 2;

FIG. 4 is a sectional view of a fixed contact structure taken along the line 44 of FIG. 1;

FIG. 5 is a front view of the fixed contact structures shown in FIG. 4;

FIG. 6 is a sectional view of the fixed contact structure taken along the line 6-6 of FIG. 4;

FIG. 7 is an exploded view of components of the fixed contact structure shown in FIGS, 4-6;

FIG. 8 is a view of the switch structure similar to FIG. 1 showing the switch structure in a cocked position just prior to switching; and

FIG. 9 is a view of the switch structure similar to FIG. 1 showing the position of the switch elements just after the switch has been operated.

With reference to FIG. 1 the switch structure there shown includes a housing 10 from which extends a common terminal support structure 12 and two line terminal support structures 14, 16. Each terminal support structure receives coaxially therein as supported by disc insulators 18 a center conductor terminal element 20 which receives a tubular center conductor 22 of a coaxial line. A flange structure, generally indicated at 24, receives and secures the outer conductor 26 of the coaxial line. While the connectors shown in the diagram are standard 3%" RETMA fifty-ohm coaxial line, it is obvious other types of connectors for high power coaxial lines may also be used.

The housing 10 is electrically connected to the three outer conductors 26 and the inner conductor terminal elements 20 are connected to the switch structure which completes a circuit between the common terminal 12 and either one of the two line terminals 14 and 16. The inner conductor terminal element 20 associated with the common terminal 12 includes a solid rod base portion (shown in FIG. 3) that has a generally V-shaped recess at its lower end within housing with a cylindrical aperture at the apex of the recess. A bearing cylinder of nylon, disposed in the cylindrical aperture 32, has a groove in it which receives the end of a switch arm structure 36. This switch arm structure is fabricated of sheet beryllium copper so that it is hollow and its mass is reduced. Adjacent its upper end are two opposed contact surfaces 38, which cooperate with one or more rows of beryllium copper contact fingers 42 suitably secured as by clamping means adjacent the lower ends of the V-shaped recess in the conductor bar of terminal element 20. Below the surfaces 38, 40 are two opposed projecting contact structures 44, each of which has a flat buffer surface 46 and a cylindrical contact surface 48.

Each projecting structure 44 cooperates with a fixed contact structure (shown in FIGS. 4-7) that is connected to the terminal element 20 of the line terminal 14, 16. As indicated best in FIG. 7, the end of each line terminal bar 20 has a cylindrical recess or bore 50 at the base of which is a threaded hole 52. Seated within bore 50 is a clamping block 54 which secures a contact ring structure 56. The base of clamping block 54 has four slots 58 therein as indicated in FIGS. 6 and 7 and an inter-mediate countersunk surface 60 which cooperates with a tapered surface 62 of the head of screw 64. Beyond the surface 60 of the clamping member 54 is a cylindrical wall portion 66 which receives a damping block 68 of polyurethane. The block 68 is secured within the cylindrical wall 66 by wedging the outer edge portions 70 of that wall inwardly as indicated in FIG. 4.

The contact ring structure 56 has a plurality of individual contact fingers 72 each of which is capable of flexing individually. These fingers surround and protrude above the buffer block 68 when it is secured as shown in FIG. 4.

In assembling this contact structure, the screw 64 is positioned in clamping block 54 so that surfaces 60 and 62 are in engagement, The bumper 68 is then positioned within recess 66 and its upper edge of that cylinder Wall is bent over to secure the bumper therein. The clamping block 54 and contact ring 56 are then disposed in bore 50. It will be noted that a hole 74 is provided in the bumper 68 through which an Allen head wrench may be inserted to tighten the screw 62. Through cooperation with the threads 52 in the base of bore 50, the head of the screw forces the clamping components of member 54 apart to lock the base of the contact ring structure 56 between the inner wall of bore 50 and periphery of the clamping block. It will be noted that, as assembled, the bumper is well down in the bore 50 and the contact fingers 72 extend outwardly a substantial distance beyond the bumper 68 to the end of the bore.

Frictionally fitted over the portion of the terminal element 20 that projects into the switch chamber is a cylinder 76 of polytetrafluoroethylene (Teflon) which functions as a dielectric barrier around the contact structure as shown in FIG. 4. The outer surface 78 of this cylinder functions as a fulcrum surface.

With reference once again to FIGS. 1 and 2, there are protruding out from switch arm 36 in opposite directions two stub shafts 80 on which are pivotally mounted two fiberglass actuating levers 82. Each actuating lever has intermediate its ends, two opposed projections 84, 86, and the lower end 88 is coupled to an actuator link 90 by means of a pin 92 that is received in slot 94 in the link. That link is connected to an actuator rod 96 which is reciprocated by an operator device 98 which may be a pneumatic cylinder as shown or other suitable actuator of either power driven or manual type. Cooperating with actuator link 90 are two stop structures 100, 102 which are movable into and out of the path of the actuator link 90 by suitable means such as control solenoids 104, 106.

Two biasing springs 110 (via pin 88) are connected between the lower ends of levers 82 and brackets 112 on the housing and each bridges the pivot connection between the switch arm 36 and the actuator lever 32.

The switch in FIG. 1 is shown completing a circuit between the common terminal 12 and the line terminal 14. In this position the switch is in uncocked position. To cock the switch, the operator 98 moves the actuator link to the left, against the control stop which is projecting into the path of that link (to the position shown in FIG. 8 in solid lines). In this position the lever projection 84 has contacted the fulcrum surface 78 of the dielectric cylinder 76 associated with the line terminal 14. No movement of the switch arm has occurred and the circuit completed between the contact fingers 42 through switch arm surface 38, and contact structure 44, to the contact fingers 72 of line terminal 14 is undisturbed.

In response to a signal to actuate the switch, the solenoid 104 is operated to retract stop member 100 and under pressure exerted by the operator 98, the actuator link 90 moves further to the left to the dotted line position shown in FIG. 8. In this dotted line position as shown, contact structure 44 has been cammed away from engagement with the contact fingers 72 of the line terminal 14 and the switch arm 36 is in an overcenter position with respect to springs 110. The biasing springs now snap the switch arm over to the position shown in FIG. 9 independently of the position of actuator link 90. During this movement under the sole influence of springs 110, the switch arm 36 is disconnected electrically from all the contact structures-both the line terminals and the common terminal and is pivoted in the nylon bearing member 30 disposed within the cylindrical recess 32. The springs drive contact surface 48 past the fingers 72 of the contact structure of the line terminal 16 and surface 46 of the contact 44 impacts the buffer block 68. The force of the switch arm on terminal 16 is absorbed by this buffer so that there is substantially no bounce and a circuit is completed between common terminal 12 and line terminal 16 via contact fingers 43 and contact 45.

After the switch has been operated to the position shown in FIG. 9, stop structure 102 may be moved up into the path of actuator link 90 and the operator 98 energized to move the actuator link to the right against stop 102 to cock the switch, again without disturbing the completed electronic circuit. While a particular embodiment of the invention has been shown and described, various modifications thereof will be obvious to those skilled in the art, and therefore, it is not intended that the invention be limited to the disclosed embodiment or to details thereof, and departures may be made therefrom within the spirit and scope of the invention as defined in the claims.

What is claimed is:

1. A coaxial line switch structure comprising a housing, first terminal means for coupling a first coaxial line to said housing, said first terminal means including a fixed contact means disposed within said housing for connection to the center conductor of said first coaxial line connected to said first terminal means, second terminal means for coupling a second coaxial line to said housing, said second terminal means including means for connection to the center conductor of said second coaxial line and means defining a pivot, a switch arm pivotally mounted on said pivot defining means, said switch arm including cont-act means for frictionally engaging said fixed contact means to complete an electrical circuit between said first terminal means and said switch arm, means for electrically connecting said switch arm to said second terminal means an actuating lever pivotally mounted on said switch arm, a fixed fulcrum surface disposed within said housing adjacent said first terminal means, and said actuating lever having a pivot surface adapted to engage said fulcrum surface, biasing means connected between said actuating lever and said housing and bridging said lever pivot surface, and operator means for moving said actuating lever from a first position to a second position in which said pivot surface contacts said fulcrum surface to place said biasing means under tension and a third posit-ion beyond said second position in which said actuating lever is rocked about said fulcrum surface to cam said contacts apart such that said biasing means accelerates said switch arm away from said first terminal means after the frictional coupling between said contacts is released.

2. The coaxial line switch structure as defined in claim 1 and further including electrical insulation interposed between said switch arm and said pivot defining means to electrically insulate said switch arm from the pivot defining portion of said second terminal means.

3. The coaxial line switch structure as claimed in claim 1 wherein said fixed contact means includes a plurality of contact members disposed in spaced relation to define an opening for receiving said switch arm contact, and damping means of impact-absorbing material disposed in said opening between said contact members for decelerating said switch arm when said switch arm is moved into engagement with said contact members.

4. A double throw switch structure comprising a housing, common terminal means mounted on said housing for connection to a first electrical transmission line, two line terminal means mounted on said housing for connection to second and third electrical transmission lines, each of said terminal means including fixed resilient electrical contact members, an electrically conductive switch arm pivotally connected to said common terminal means and including two contact members for frictional engagement with corresponding contact members associated with said two line terminal means, a fixed fulcrum surface disposed within said housing adjacent each of said line terminal means, an actuating lever pivotally mounted on said switch arm and including pivot surface means adapted to engage said fulcrum surfaces, biasing means connected to said actuating lever and bridging said lever pivot surface means, and operator means for moving said actuating lever from a first position to a second position in which said pivot surface means contacts a fulcrum surface and a third position beyond said second position in which said biasing means is placed under tension and said actuating lever is rocked about said fulcrum surface to cam the switch arm contact member away from the engaged line terminal contact member such that said tensioned biasing means accelerates said switch arm away from the one line terminal means after the frictional coupling between said contact members is released and into engagement with the other line terminal means to complete an electrical circuit between said common terminal means and said other line terminal means.

5. The switch structure as claimed in claim 4 and further including means from latching said actuating lever in said second position with said biasing means under tens-ion to cock said switch structure.

6. The switch structure as claimed in claim 4 wherein said switch arm contact is cylindrical in configuration and includes a circular end surface and each of said fixed contact members associated with said line terminal means includes a plurality of resilient contact elements arranged in a circle and a damping member of impactabsorbing material disposed in the center of said circle of contact elements for receiving the circular surface of said switch arm contact member when the cylindrical surface of that member engages said circle of contact elements.

7. The switch structure as defined in claim 4 and further including electrical insulation interposed between said switch arm and said common terminal means to electrically insulate said switch arm from said common terminal means during movement of said switch arm between positions of engagement with said line terminal means.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner. 

1. A COAXIAL LINE SWITCH STRUCTURE COMPRISING A HOUSING, FIRST TERMINAL MEANS FOR COUPLING A FIRST COAXIAL LINE TO SAID HOUSING, SAID FIRST TERMINAL MEANS INCLUDING A FIXED CONTACT MEANS DISPOSED WITHIN SAID HOUSING FOR CONNECTION TO THE CENTER CONDUCTOR OF SAID FIRST COAXIAL LINE CONNECTED TO SAID FIRST TERMINAL MEANS, SECOND TERMINAL MEANS FOR COUPLING A SECOND COAXIAL LINE TO SAID HOUSING, SAID SECOND TERMINAL MEANS INCLUDING MEANS FOR CONNECTION TO THE CENTER CONDUCTOR OF SAID SECOND COAXIAL LINE AND MEANS DEFINING A PIVOT, A SWITCH ARM PIVOTALLY MOUNTED ON SAID PIVOT DEFINING MEANS, SAID SWITCH ARM INCLUDING CONTACT MEANS FOR FRICTIONALLY ENGAGING SAID FIXED CONTACT MEANS TO COMPLETE AN ELECTRICAL CIRCUIT BETWEEN SAID FIRST TERMINAL MEANS AND SAID SWITCH ARM, MEANS FOR ELECTRICALLY CONNECTING SAID SWITCH ARM TO SAID SECOND TERMINAL MEANS AN ACTUATING LEVER PIVOTALLY MOUNTED ON SAID SWITCH ARM, A FIXED FULCRUM SURFACE DISPOSED WITHIN SAID HOUSING ADJACENT SAID FIRST TERMINAL MEANS, AND SAID ACTUATING LEVER HAVING A PIVOT SURFACE ADAPTED TO ENGAGE SAID FULCRUM SURFACE, BIASING MEANS CONNECTED BETWEEN SAID ACTUATING LEVER AND SAID HOUSING AND BRIDGING SAID LEVER PIVOT SURFACE, AND OPERATOR MEANS FOR MOVING SAID ACTUATING LEVER FROM A FIRST POSITION TO A SECOND POSITION IN WHICH SAID PIVOT SURFACE CONTACTS SAID FULCRUM SURFACE TO PLACE SAID BIASING MEANS UNDER TENSION AND A THIRD POSITION BEYOND SAID SECOND POSITION IN WHICH SAID ACTUATING LEVER IS ROCKED ABOUT SAID FULCRUM SURFACE TO CAM SAID CONTACTS APART SUCH THAT SAID BIASING MEANS ACCELERATES SAID SWITCH ARM AWAY FROM SAID FIRST TERMINAL MEANS AFTER THE FRICTIONAL COUPLING BETWEEN SAID CONTACTS IS RELEASED. 